<i>sox9b</i> is expressed in the pancreaticobiliary ductal system, and the <i>sox9b^fh313</i> lesion is a nonsense mutation.

<p>(A–D) <i>sox9b</i> expression is observed in the head and fin buds (arrowheads in A–C), as well as the notochord (n) and part of the foregut endoderm (bracket) at 30 hpf (A). At 48 hpf, <i>sox9b</i> expression is observed in the liver bud (arrow) and hepatopancreatic duct primordium (bracket) (B). At 60 hpf, <i>sox9b</i> expression covers the intra- (arrow) and extrahepatic (bracket) ducts (C), and extends to the intrapancreatic ducts by 72 hpf (white arrow, D). Dorsal views, anterior (A) to the left. (E) Genomic DNA sequence of wild-type (left panel) and <i>sox9b^fh313</i> mutant (right panel) showing an A>T transversion at position 302 of the coding sequence. This mutation leads to a stop codon at amino acid Lys68. (F) Schema of Sox9b depicting the localization of the amino acid affected by the <i>fh313</i> mutation leading to a stop codon upstream of the HMG box DNA-binding domain. IPD, intrapancreatic duct; IHD, intrahepatic duct; HPD, hepatopancreatic duct; HMG, high-mobility group; aa, amino acid.